Typhoon Hinnamnor intensified back to the equivalent of a major hurricane west of Okinawa on Saturday night. At 11:00 p.m. EDT on Saturday the center of Typhoon Hinnamnor was located at latitude 26.6°N and longitude 124.4°E which put it about 205 miles (330 km) west of Okinawa. Hinnamnor was moving toward the north at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 120 m.p.h. (195 km/h) and there were wind gusts to 150 m.p.h. (240 km/h). The minimum surface pressure was 951 mb.

Typhoon Hinnamnor strengthened back to the equivalent of a major hurricane over the East China Sea west of Okinawa on Saturday night. Two concentric eyewalls appeared to have formed in the middle of Typhoon Hinnamnor. A small inner eye with a diameter of 12 miles (19 km) was that the center of Hinnamnor’s circulation. The inner eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. A much larger, outer eyewall with a diameter of 100 miles (160 km) surrounded the inner eye and eyewall.

The formation of concentric eyewalls caused the size of the circulation around Typhoon Hinnamnor to increase. Winds to typhoon force extended out 70 miles (110 km) from the center of Hinnamnor. Winds to tropical storm force extended out 270 miles (435 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 22.1. The Hurricane Size Index (HSI) was 29.3 and the Hurricane Wind Intensity Size Index (HWISI) was 51.4. Typhoon Hinnamnor was capable of causing widespread major damage.

Typhoon Hinnamnor will move through an environment favorable for intensification during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Hinnamnor could intensify until the inner eyewall starts to weaken and an eyewall replacement cycle begins. Hinnamnor will move closer to the upper level westerly winds in the middle latitudes on Monday. The vertical wind shear will increase when that happens and Hinnamnor will weaken.

Typhoon Hinnamnor will move around the western end of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Hinnamnor toward the north during the next 24 hours. Hinnamnor will move toward northeast when it reaches the westerly winds in the middle latitudes. On its anticipated track Typhoon Hinnamnor will move east of Shanghai in 24 hours. Hinnamnor could approach South Korea in 36 hours.